A gas turbine engine may be used to power various types of vehicles and systems. A particular type of gas turbine engine that may be used to power aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine conventionally includes, for example, five major sections: a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section is typically positioned at the inlet section of the engine and includes a fan that induces air from the surrounding environment into the engine and accelerates a fraction of this air toward the compressor section. The remaining fraction of air induced into the fan section is accelerated into and through a bypass plenum and out the exhaust section.
The compressor section raises the pressure of the air it receives from the fan section, and the resulting compressed air then enters the combustor section, where a ring of fuel nozzles injects a steady stream of fuel into a combustion chamber formed between inner and outer liners. The fuel and air mixture is ignited to form combustion gases, which drive rotors in the turbine section for power extraction. The gases then exit the engine at the exhaust section.
Known combustors include inner and outer liners that define an annular combustion chamber in which the fuel and air mixture is combusted. During operation, a portion of the airflow entering the combustor is channeled through the combustor outer passageway for attempting to cool the liners and diluting a main combustion zone within the combustion chamber. Some combustors are dual walled combustors in which the inner and outer liners each have so-called “hot” and “cold” walls. These arrangements may enable impingement-effusion cooling in which cooling air flows through cavities formed between the hot and cold walls. In order to maximize cooling, seals may be provided between the respective hot and cold walls at the forward and aft edges to seal the cavities. Typically, these seals are fixed seals.
A consequence of the dual walled combustor design is the inherent difference in operating temperature between the walls of the liners. For example, the hot walls are subjected to high temperature combustion gases and thermal radiation, resulting in thermal stresses and strains, while the cold walls are shielded from the combustion gases and run much cooler. Differential operating temperatures result in differential thermal expansion and contraction of the combustor components. Such differential thermal movement occurs both axially and radially, as well as during steady state operation and during transient operation of the engine as power is increased and decreased. This movement may particularly cause undesirable leakage or stress issues with the seals of the respective liner walls.
Accordingly, it is desirable to provide combustors with liner seals that accommodate differential thermal movement therebetween, while also minimizing undesirable leakage of cooling air. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.